diff options
Diffstat (limited to 'edid_injector.c')
| -rw-r--r-- | edid_injector.c | 138 |
1 files changed, 115 insertions, 23 deletions
diff --git a/edid_injector.c b/edid_injector.c index b938d85..a87fc56 100644 --- a/edid_injector.c +++ b/edid_injector.c @@ -44,7 +44,7 @@ #define BAUDRATE 100000
#define TWI_BAUDSETTING TWI_BAUD(F_CPU, BAUDRATE)
-#define EDID_SLAVE_ADDRESS 0xA0
+#define EDID_SLAVE_ADDRESS 0x50
/* TWIC is on the display side */
TWI_t * const twiDisplay = &TWIC;
@@ -65,23 +65,39 @@ ISR(TWIE_TWIS_vect) TWI_SlaveInterruptHandler(&twisHost);
}
+#define EDID_BLOCK_LENGTH 128
-void TWIC_SlaveProcessData(void)
+static uint8_t edid_data[EDID_BLOCK_LENGTH];
+static uint8_t edid_offset;
+static uint8_t recvbuf[1];
+
+void TWIC_SlaveProcessData(TWI_Slave_t * const twi)
{
+ if( twi->bytesReceived ) {
+ edid_offset = twi->recvData[0];
+ }
+ twi->sendData = edid_data + edid_offset;
+ twi->bytesToSend = sizeof(edid_data) - edid_offset;
}
void edid_initHostTWI(void)
{
/* Initialize TWI slave. */
- TWI_SlaveInitializeDriver(&twisHost, twiHost, TWIC_SlaveProcessData);
+ TWI_SlaveInitializeDriver(&twisHost,
+ twiHost,
+ TWIC_SlaveProcessData);
+
TWI_SlaveInitializeModule(&twisHost,
EDID_SLAVE_ADDRESS,
- TWI_SLAVE_INTLVL_MED_gc );
+ TWI_SLAVE_INTLVL_HI_gc,
+ recvbuf,
+ sizeof(recvbuf) );
}
void edid_initDisplayTWI(void)
{
/* Initialize TWI master. */
+ twimDisplay.status = TWIM_STATUS_READY;
TWI_MasterInit(&twimDisplay,
twiDisplay,
TWI_MASTER_INTLVL_LO_gc,
@@ -99,52 +115,128 @@ void edid_initDisplayTWI(void) }
+uint8_t edid_checkData(uint8_t const *ediddata)
+{
+ uint8_t checksum = 0;
+ for(uint8_t i = 0; i < EDID_BLOCK_LENGTH; i++) {
+ checksum += ediddata[i];
+ }
+ if( 0 != checksum ) {
+ return 1; /* checksum failed */
+ }
+
+ if( 0 != ediddata[0] ) {
+ return 2; /* headerbyte[0] != 0 */
+ }
+
+ for(uint8_t i = 1; i < 7; i++) {
+ if( 0xff != ediddata[i] ) {
+ return 3; /* headerbyte[1..6] != 0xff */
+ }
+ }
+
+ if( 0 != ediddata[7] ) {
+ return 4; /* headerbyte[7] != 0 */
+ }
+
+ return 0; /* EDID data passed checks */
+}
+
uint8_t edid_genChecksum(uint8_t *ediddata)
{
uint8_t bytessum = 0;
- for(size_t i = 0; i < 127; i++) {
+ for(uint8_t i = 0; i < EDID_BLOCK_LENGTH-1; i++) {
bytessum += ediddata[i];
}
- return 0xff - bytessum;
+ return 0xff - bytessum + 1;
}
-void edid_readFromDisplayToEEPROM(void)
+uint8_t edid_readFromDisplayToEEPROM(void)
{
- uint8_t displayedid[128];
- memset(displayedid, 0, sizeof(displayedid));
+ uint8_t const offset[1] = {0x00};
+ uint8_t displayedid[EDID_BLOCK_LENGTH];
+
+ uint8_t error = 0;
+ uint8_t retry = 20;
+ while( retry-- ) {
+ TWI_MasterForceIdle(&twimDisplay);
+ delay_ms(1);
+
+ /* set EDID offset to 0 */
+ if( !TWI_MasterWriteRead(&twimDisplay,
+ EDID_SLAVE_ADDRESS,
+ offset,
+ sizeof(offset),
+ displayedid,
+ sizeof(displayedid) ) ) {
+ PORTB.OUTCLR = (1<<3);
+ PORTB.OUTSET = (1<<3);
+ };
+
+ while( !TWI_MasterReady(&twimDisplay) ) {
+ delay_ms(1);
+ }
+ delay_ms(1);
- /* read 128 EDID bytes from display */
+ if( twimDisplay.result != TWIM_RESULT_OK ) {
+ error = 1;
+ continue;
+ }
+
+ if( edid_checkData(displayedid) ) {
+ error = 2;
+ continue;
+ }
+
+ break;
+ }
+ if( !retry ) {
+ return error;
+ }
/* set EDID Extension Block count / flags to zero */
+ displayedid[126] = 0;
/* recalculate checksum */
displayedid[127] = edid_genChecksum(displayedid);
/* write EDID information to EEPROM */
+ memcpy(edid_data, displayedid, EDID_BLOCK_LENGTH);
+
+ return 0;
}
int main(void)
{
- edid_initHostTWI();
+ memset(edid_data, 0, sizeof(edid_data));
- edid_initDisplayTWI();
+ PORTB.DIR = (1<<3);
+ PORTE.DIR = (1<<2) | (1<<3);
+ edid_initHostTWI();
+ edid_initDisplayTWI();
+ /* Enable LO interrupt level. */
+ PMIC.CTRL |=
+ PMIC_LOLVLEN_bm
+ | PMIC_MEDLVLEN_bm
+ | PMIC_HILVLEN_bm;
sei();
+ delay_ms(20);
- #if 0
- TWI_MasterWriteRead(&twiMaster,
- SLAVE_ADDRESS,
- &sendBuffer[BufPos],
- 1,
- 1);
-
-
- while (twiMaster.status != TWIM_STATUS_READY) {
- /* Wait until transaction is complete. */
- }
+ #if 1
+ /* EDID standard requires a host to wait for 20ms after switching +5V
+ * supply to display before performing the first readout attempt.
+ * Since uC supply == display +5V supply we're waiting 20ms here.
+ */
+ for(;;) {
+ edid_readFromDisplayToEEPROM();
+ delay_ms(1000);
+ }
#endif
+
+ return 0;
}
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